In addition to providing access to information, the World Wide Web (also referred to as the “Web”) has increasingly become a medium that is used to search for, shop for and order items (such as products, services and/or information) that are available for purchase, rent, lease, license, trade, evaluation, sampling, subscription to, etc. In many circumstances, a user may visit the Web site of a Web merchant or other online retailer that provides one or more items (sometimes referred to as a “Web store”), such as to view information about the items, give an instruction to place an order for one or more items, and provide information needed to complete the purchase (e.g., payment and shipping information). After receiving an order for one or more items, the online retailer then fulfills the order by providing the ordered items to the indicated recipient, such as by delivering product items electronically (e.g., music downloaded over the Internet) and/or through physical distribution channels (e.g., shipment via a governmental postal service or private common carrier, such as for paperback books). Similarly, some service items may be provided electronically (e.g., providing email service), while others may be provided physically (e.g., performing cleaning services at the purchaser's house).
While access to information about items via the Web provides many benefits, various problems also exist. As one example, given the large numbers of items that may be available from various online retailers, it can be difficult for a user to identify particular items that may be of interest. In addition, while various approaches to automatically generating recommendations for users have been tried, such generated recommendations have various problems, including that any given approach to generating recommendations is typically useful only in certain limited situations, if at all.